Five Darfur aid workers employed by the international medical charity, Médecins Sans Frontières (MSF), were abducted Wednesday night, the agency said.

Two Sudanese staff were later released but three others – a Canadian nurse, a French coordinator and an Italian doctor – were still being held by their abductors on Thursday. MSF did not reveal whether it had any information on the identity of those who seized the staff.

“MSF is currently working to get more information about the circumstances and the motives surrounding this abduction,” it said in a statement on its website. It added that it was doing “everything it can to determine their whereabouts and ensure their safe and swift return.”

The staff, who work for the Belgian branch of MSF, were abducted in Serif Umra in North Darfur.

Two other branches of MSF were ordered out of Darfur by the Sudanese government last week. The agency said in a statement then that the government had justified its action on the grounds that it could not guarantee the safety of staff after the announcement that the International Criminal Court at The Hague would issue a warrant for the arrest of President Omar al-Bashir on charges of war crimes and crimes against humanity over his conduct of the war in Darfur.